This flood damaged the sewer line at Main and the St. Vrain River in Longmont uses pumps to get rid of the sewage at a cost of $70,000 a month. It will remain in use until next year. (Cliff Grassmick / Daily Camera)

The pump keeps going at the Main Street bridge.

It was supposed to have been shut down by spring, a temporary way to work around a flood-damaged sewer line serving Southmoor Park. But "temporary" is taking longer than everyone thought. Now it may be 2015 before a replacement gets built.

At $60,000 to $70,000 a month to fuel, operate and monitor the pump round the clock, that's not a cheap substitute.

"It has been (frustrating), yes," said Chris Huffer, a senior civil engineer for the city of Longmont. "It's a concern for a lot of people."

What's causing the delays? It's one part fish and one part flood.

The fish part came, appropriately enough, from Colorado Parks and Wildlife, which wanted to see the city include a "fish ladder" for a species of minnow found mainly in the St. Vrain River. (As recently as 2010, the St. Vrain had three types of fish that were special state-listed species, and two more that were considered to be declining.)

"Unfortunately, they weren't able to give us a good description of what the fish ladder should be," Huffer said.

At the same time, a state-sponsored hydrology study west of town were suggesting that Longmont might have to think bigger in its flood prevention efforts.

Traditionally, a 100-year flood for Longmont — the sort that has a 1 percent chance of occurring in any year — has a flow rated at 10,000 cubic feet per second (cfs). But the study, commissioned by the Colorado Department of Transportation and the Colorado Water Conservation Board, said the area west of Longmont had been underrated and that the true 100-year number could be 30 percent higher.

For Longmont, which has been planning flood control measures to let a 100-year flood pass safely through the city, that could mean some redesign. And since one of the earliest projects in that plan is a replacement of the Main Street bridge — slated to begin late this year — it made sense to move the sewer line rather than rebuild it, Huffer said.

So, instead of passing beneath the bridge, the line will be shifted east to Interceptor F in the Harvest Junction area, a spot with fewer issues. The city expects to finish the design by the end of the year, begin construction in early 2015 and wrap it up before next spring's runoff.

Until then, the pump keeps going. And the bills keep coming in.

Eventually, some money should, too; the pump is a Federal Emergency Management Agency-eligible expense. That means FEMA can cover 75 percent of the cost, with the state covering another 12.5 percent.

It's gotten a little less expensive to maintain since winter ended, Huffer said. But not any less frustrating.